Honeydew
/ˈhʌniˌdu/
Definition
Honeydew is a sticky, sugar-rich liquid excreted by sap-feeding insects such as aphids, scale insects, whiteflies, and mealybugs as they feed on plant phloem, the tissue that carries sugars. It collects on leaves, stems, fruit, and nearby surfaces. Unlike plant sap or nectar, it is insect waste. Its presence often signals an active pest infestation and can support the growth of sooty mold, a dark surface fungus.
Effects on Plants
- Sticky leaf surfaces: It coats leaves, stems, fruit, pots, and nearby furniture, reducing appearance and making plants feel tacky. Heavy deposits can also interfere with gas exchange on the leaf surface.
- Sooty mold growth: Dark fungal growth often develops on top of it. This mold does not invade plant tissue, but it can block light and reduce photosynthesis, which may weaken heavily affected plants.
- Pest clue: Its presence is a strong sign of sap-feeding insects such as aphids, scale, whiteflies, or mealybugs. Finding it can help narrow the diagnosis even when the insects are hidden under leaves or along stems.
- Ant activity nearby: Ants are often attracted to it and may protect the insects producing it from natural enemies. That relationship can make biological control less effective until the ant activity is reduced.
Related Terms
Whitefly
Whitefly refers to several tiny sap-feeding insect pests related to aphids and scale insects. Adults are moth-like…
Scale
Scale refers to a group of small sap-sucking insect pests that attach to stems, leaves, or branches and feed by…
Sooty mold
Sooty mold refers to a dark, soot-like coating of fungi that grows on sugary honeydew left by sap-feeding insects such…
Leaf miner
Leaf miner refers to the larval stage of certain insects, most often flies, moths, beetles, or sawflies, that feed…
Thrips
Thrips are tiny, slender insects that feed by scraping plant surfaces and sucking out cell contents. In gardens…
Spider mites
Spider mites are tiny plant-feeding arachnids, not insects, that pierce leaf cells and suck out contents. They usually…
Integrated pest management (IPM)
Integrated pest management (ipm) is a pest control strategy used in gardens, greenhouses, farms, and landscapes that…